Solution for Measuring Water Pressure and Differential Pressure in HVAC Systems – Dwyer Pressure Sensors Series 626, 628, 629C, 629HPL

Solution for Measuring Water Pressure and Differential Pressure in HVAC Systems – Dwyer Pressure Sensors Series 626, 628, 629C, 629HPL

Solution for Measuring Water Pressure and Differential Pressure in HVAC Systems – Dwyer Pressure Sensors Series 626, 628, 629C, 629HPL

Posted on: 09/06/2025

Water pressure sensors are devices used to measure and monitor the pressure or differential pressure of liquids in systems such as water supply, HVAC, wastewater treatment, and industrial automation. These sensors convert pressure into electrical signals (commonly 4–20 mA or 0–10 V), allowing data to be transmitted to a central controller or PLC for accurate and safe system operation and alerts.

Dwyer Instruments (USA) is one of the world’s leading manufacturers in the field of measurement and control devices. Among their products, the pressure and differential pressure sensors from the 626, 628, 629C, and 629HPL series are widely applied in industrial processes, water supply and drainage, HVAC systems, and automation.

1. What is a Dwyer Pressure Sensor?

A Dwyer pressure sensor is a device used to measure absolute pressure, differential pressure, or gauge pressure in air, steam, or liquid systems. The pressure signal is converted into an electrical signal (typically 4–20 mA or 0–10 V) for monitoring, alerting, or automatic control purposes within the system.

Dwyer offers specialized sensor series for measuring water and liquid pressure, including:

  • Series 626 – liquid pressure sensors with a robust stainless steel body, suitable for industrial and HVAC applications.
  • Series 628 – sensors suitable for liquids and gases, offering stable operation and high accuracy, ideal for medium to high-pressure environments.
  • Series 629C – designed to measure water and non-corrosive liquids, with a wide measurement range and modern electronic integration.
  • Series 629HPL – high-performance (HPL) pressure sensors, suitable for applications requiring high accuracy and reliability in monitoring cold water, hot water, or complex liquid transmission systems.

These series are widely applied in HVAC systems, water supply systems, booster pumps, boiler monitoring, and industrial automatic control systems.

2. Overview of Features and Advantages of Dwyer Pressure Sensor Series

2.1 Series 628 – Industrial Pressure Sensors

  • High accuracy: 1.0% FS, with 0.5% RSS (Root Sum Square).
  • Enclosure: NEMA 4X (IP66) rated, dust and water-resistant, suitable for harsh environments.
  • Wetted materials: 316L stainless steel, corrosion-resistant, compatible with various liquids and gases.
  • Power supply: 10–30 VDC for 4–20 mA signal; 13–30 VDC for 0–10 VDC signal.
  • Applications: pumps, irrigation systems, submersible pumps, and pressure monitoring in industrial processes.

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2.2 Series 629C – Water Differential Pressure Sensors

  • Differential pressure measurement: suitable for both liquids and gases, ±0.5% FS accuracy.
  • Enclosure: NEMA 4X (IP66), dust and water-resistant.
  • Output signal: options include 4–20 mA (2-wire) or 0–5 VDC, 1–5 VDC, 0–10 VDC, 2–10 VDC (3-wire).
  • Optional LCD display: shows measured values directly without separate power supply.
  • Applications: pressure monitoring in filtration systems, heat exchangers, pumps, chillers, and HVAC equipment.

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2.3 Series 629HPL – High Static Pressure Differential Sensors

  • Differential pressure measurement under high static pressure: suitable for high static pressure environments, ±0.5% FS accuracy.
  • Output signal: 4–20 mA or 0–10 VDC options.
  • Applications: pressure monitoring in industrial processes requiring differential measurement under high static pressure.

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3. Comparison of Pressure Sensor Series

Series Accuracy Measurement Type Static Pressure Output Signal LCD Display Main Applications
628 1.0% FS Absolute/Gauge Pressure No Limit 4–20 mA, 0–10 VDC No Pumps, irrigation, industrial processes
629C ±0.5% FS Wet Differential Pressure No Limit 4–20 mA, 0–5/1–5/0–10/2–10 VDC Optional Filtration, heat exchangers, pumps, HVAC
629HPL ±0.5% FS High Differential Pressure under Static Pressure High 4–20 mA, 0–10 VDC No Industrial processes with high static pressure

4. Selecting the Appropriate Model by Measurement Range and Output Signal

>A list of popular pressure sensor models ranging from 0–10 bar to 0–16 bar, with 4–20 mA or 0–10 V output, helps engineers and system designers make accurate and easy selections.

No. Sensor Name Measurement Range Output Signal Series Model
1 Water Pressure Sensor 0–10 bar 4–20 mA 626 626-75-GH-P1-E1-S1
2 Water Pressure Sensor 0–10 bar 0–10 V 626 626-75-GH-P1-E1-S5
3 Water Pressure Sensor 0–16 bar 4–20 mA 626 626-90-GH-P1-E1-S1
4 Water Pressure Sensor 0–16 bar 0–10 V 626 626-90-GH-P1-E1-S5
5 Water Pressure Sensor 0–10 bar 4–20 mA 628 628-75-GH-P1-E1-S1
6 Water Pressure Sensor 0–10 bar 0–10 V 628 628-75-GH-P1-E1-S5
7 Water Pressure Sensor 0–16 bar 4–20 mA 628 628-90-GH-P1-E1-S1
8 Water Pressure Sensor 0–16 bar 0–10 V 628 628-90-GH-P1-E1-S5
9 Water Differential Pressure Sensor — 4–20 mA 629C 629C-05-CH-P1-E1-S1
10 Water Differential Pressure Sensor — 0–10 V 629C 629C-05-CH-P1-E1-S3
11 Water Differential Pressure Sensor (LCD 3V) — 4–20 mA 629C 629C-05-CH-P2-E1-S1-3V
12 Water Differential Pressure Sensor — 4–20 mA 629HPL 629HLP-06-P2-S1
13 Water Differential Pressure Sensor — 0–10 V 629HPL 629HLP-06-P2-S5

Notes:

  • “P1” usually indicates pressure connection type 1 (thread type), “E1” indicates standard power supply.
  • “75” corresponds to 0–10 bar range, “90” to 0–16 bar.
  • 629C is the standard wet differential sensor, while 629HPL is designed for higher static pressure differential applications.
  • Series using “GH” are designed for water and harsh environment compatibility.

5. DLK – Official Distributor of Dwyer Pressure Sensors in Vietnam

DLK – Long Khanh Electrical Technical Trading Co., Ltd is the official partner of Dwyer Instruments in Vietnam, distributing the full range of pressure sensors including SERIES 629, 629HPL, and 629C.

When purchasing from DLK, you are guaranteed:

  • 100% genuine products with full CO and CQ documentation.
  • Professional advice to select the correct model according to technical requirements.
  • Competitive pricing with on-site technical support.
  • Fast nationwide delivery.

Contact Long Khanh Electrical Technical Trading Co., Ltd (DLK)

  • Address: G6/14 Tran Van Giau, Le Minh Xuan, Binh Chanh District, Ho Chi Minh City
  • Office: 111/7 Vuon Lai, Phu Tho Hoa Ward, Tan Phu District, Ho Chi Minh City
  • Website: https://dlk.com.vn/
  • Email: info@dlk.com.vn

Hotline: 070 357 0101 – 093 279 2697

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